Fritz S.C, Baker P.A, Lowenstein T.K, Seltzer G.O, Rigsby C.A, Dwyer G.S, Tapia P.M, Arnold K.K, Ku T.L, Luo S.D.  2004.  Hydrologic variation during the last 170,000 years in the southern hemisphere tropics of South America. Quaternary Research. 61(1):95-104.